Typical personal emergency response systems (PERS) employ a portable alarm unit worn by a subscriber. The alarm unit (typically a pendant), when actuated by the subscriber, transmits a wireless alarm signal to a fixed base station located within the subscriber's premise. When the base station receives the alarm signal, the base system transmits an alert signal via a telephonic communication link to a central dispatch center. A dispatcher at the central dispatch center attempts to verify the alert via two-way voice communications with the subscriber via the base station, which typically has a speaker phone capability. Depending upon information or lack thereof received by the dispatcher from the subscriber, directions may then be issued by the dispatcher to dispatch aid to the residence from which the alert signal was received. PERS of this type have proven to be a reasonably effective tool for responding to the needs of elderly and/or infirm persons confined to their residences and/or persons living alone.
The typical subscriber who uses a PERS subscribes to only a single voice grade telephone line corresponding to a single telephone number. That is, the PERS subscriber's telephone line has not been configured by the telephone service provider to support a bandwidth greater than the standard voice grade bandwidth of 400 to 3400 Hz.
There may be occasions where the subscriber of a PERS (or another person at the subscriber's premise) having access to only a single voice grade subscriber telephone line wishes to transmit a continuous video signal, and not merely a single freeze frame image, to the central dispatch center in addition to having two-way voice communication with the central dispatch center in order that the person's physical condition may be more properly assessed by the dispatcher. Accordingly, it would be desirable to be able to send a continuous video signal from the subscriber's location to the central dispatch center over the same subscriber voice grade telephone line that is being used for two-way voice communication.